Melting Arctic sea ice could be altering jet stream

More studies look at links to extreme weather.

The rapidly warming Arctic isn’t noteworthy only for its own sake. Changes there affect the rest of the planet in a number of ways. Recently, there has been a lot of interest in whether the dwindling Arctic summer sea ice could be weirding the weather in the mid-latitudes.

There have been a number of recent summer extremes—Russia’s hellish summer in 2010, the drought in the US last summer, a very wet 2011 in Korea and Japan, plus a streak of soggy summers in the UK. There have been suggestions that lower summer sea ice in the Arctic could be gumming up the jet stream and contributing to these events, but some climate scientists aren’t so sure. A new study in Nature Climate Change brings more evidence to the table in support of the idea.

Qiuhong Tang and Xuejun Zhang, of the Chinese Academy of Sciences, and Jennifer Francis, of Rutgers, decided to look for patterns of atmospheric change correlated with the loss of Arctic summer sea ice and the decline of early summer snow cover. Using reanalyses, which generate global datasets based on all the available measurements, they examined how the lower, middle, and upper troposphere responded to variations in sea ice and snow cover from 1979 (the start of the satellite era) to 2012.

They found modest correlations with the behavior of high-level winds and the differences in atmospheric pressure that drive them, more so for sea ice than snow cover. Over most regions, the average position of the jet stream moved a little northward when summer sea ice was smaller, while the opposite was true for the western edges of continents. The high-level, west-to-east winds of the jet stream also slowed a bit.

Those two factors are consistent with the hypothesized link between sea ice and weather extremes. When the jet stream slows, it gets wigglier, with ponderous meanders extending north and south. Because the temperature difference across the jet stream is so large, these slow-moving excursions can lead to temperature extremes. The early loss of snow cover can exacerbate this, as it means soils can dry out earlier in the summer. Not only does that make a region susceptible to drought, but low soil moisture allows temperatures to rise higher.

Another recent paper published in Environmental Research Letters focused on Northern Europe, using different techniques. There, an unusual run of six wet summers left people wondering if Arctic sea ice loss could have contributed.

Looking through the data, University of Exeter researcher James Screen saw that wet conditions are associated with the jet stream coming south from its average position. Conversely, it’s drier when it stays far to the north. Screen ran two climate model simulations: one in which Arctic sea ice was present at its 1979 extent and one at its diminished 2009 extent. Each simulation was repeated for a century’s worth of summers to calculate the average position of the jet stream over Europe.

Consistent with the study by Tang, Zhang, and Francis, the lower sea ice extent in the model was associated with the jet stream moving a little southward over Europe as part of its amplified “wiggliness.” That brought more precipitation to Northern Europe in the model simulations.

However, Screen emphasizes that these things vary quite a lot from year to year on their own, and the simulated sea ice impact was only a slight shift. “This means that whilst low sea ice coverage increases the risk of wet summers, other factors can easily negate this influence and lead to dry summers during depleted ice conditions or wet summers during extensive ice conditions,” he writes.

The details of how declining Arctic sea ice affects atmosphere circulation and weather patterns is very much a hot topic for research and debate, particularly when discussing potential contributions to specific, extreme weather events. In an article accompanying the Tang, Zhang, and Francis study in Nature Climate Change, NOAA researcher James Overland notes, “Skeptics remain unconvinced that Arctic/mid-latitude linkages are proven, and this work will do little to change their viewpoint.” He’s not talking about the self-professed "climate skeptics" who reject most of the conclusions of climate science here, but rather researchers in the field who have weighed in on this hypothesis.

“As most changes in the frequency of mid-latitude extreme events have occurred only in the past decade,” Overland writes, “there is insufficient data to formally resolve the debate on whether these events are purely random or if their occurrence is enhanced by Arctic cryosphere changes.” Work like this, however, is informing that debate.

78 Reader Comments

Ugh, I hate it when the Ars articles already contain the disclaimer from the scientists that show them to be the rational science-based individuals who don't want their research to be used to make assumptions stronger than the data supports, instead of the for-profit, big-government-loving, Al-Gore-Worshiping hippie radicals who just want grants that some people want to pretend them to be.

Consistent with the study by Tang, Zhang, and Francis, the lower sea ice extent in the model was associated with the jet stream moving a little southward over Europe as part of its amplified “wiggliness.” That brought more precipitation to Northern Europe in the model simulations.

Europe is already pretty rainy. Maybe the future will be more Pacific Northwesty. Or if the gulf stream shuts down, really snowy.

Ugh, I hate it when the Ars articles already contain the disclaimer from the scientists that show them to be the rational science-based individuals who don't want their research to be used to make assumptions stronger than the data supports, instead of the for-profit, big-government-loving, Al-Gore-Worshiping hippie radicals who just want grants that some people want to pretend them to be.

It takes all the fun out of the comment section.

See I don't get this. All Al Gore did was use the celebrity and public exposure he gained from being VP and his training as a journalist and utilize the same tactics the oil industry fat cats. Give the guy credit, he won a nobel prize, an oscar, a pulitzer, plus he's worth several hundred million dollars --- and he's trying to save the world.

Thanks for the article. Very interesting for me, as I've been living in the UK for the last few year, and "enjoying" its nice weather. In any case, I bet the article is not as entertaining as (some of) the comments are going to be.

Thanks for the article. Very interesting for me, as I've been living in the UK for the last few year, and "enjoying" its nice weather. In any case, I bet the article is not as entertaining as (some of) the comments are going to be.

Ugh, I hate it when the Ars articles already contain the disclaimer from the scientists that show them to be the rational science-based individuals who don't want their research to be used to make assumptions stronger than the data supports, instead of the for-profit, big-government-loving, Al-Gore-Worshiping hippie radicals who just want grants that some people want to pretend them to be.

Just wondering if an altered jet stream could be melting the Arctic sea ice?

Hmm... not in any way I'm aware of.

I think he might have been getting at the fact that the research is still preliminary in a way and an effect opposite of what was thought could still be found? For example, (just speculation here, not saying this is what is going on) I would assume that the movement of the Jet would effect the Hadley/Ferrel/Polar cell circulations, if these circulations were indeed effected and broadened to reach latitudes they were not normally akin to this could cause more ice melt in the north perhaps? That being said though I think this research is quite interesting and will be interested in future findings.

I hope this doesn't cause the Jetstream to be wigglier. This is what caused hurricane sandy,. the Jetstream dipped and allowed sandy to turn and interact with a cold system. The jet stream is usually why NYC area doesn't get a lot of hurricanes. It is when it does something unusual at the right time that we get them.

Is this Ars Technica, professional outlet for science and technology journalism, or Facebook? "Weird" is not a verb. There is no such thing as "weirding". I've seen a number of articles this year which use this type of "social media language" and it needs to stop. If you're a professional writer (and editors), act like it.

See I don't get this. All Al Gore did was use the celebrity and public exposure he gained from being VP and his training as a journalist and utilize the same tactics the oil industry fat cats. Give the guy credit, he won a nobel prize, an oscar, a pulitzer, plus he's worth several hundred million dollars --- and he's trying to save the world.

Thanks for proving my point about "Generation Social". What's next, are you going to go find a link from the "Urban Dictionary" and use that as a "source," too?

What a joke. Yes, weird must be a verb now, because those are legitimate reference sources for the English language. I sincerely hope you never go into any form of teaching where language usage details matter. Pull your head out your ass.

You're clueless. Do you also object to the verbs access, mail, sleep, ship, drink, and the thousands of other nouns that have been turned into verbs over the course of a thousand or more years?

See I don't get this. All Al Gore did was use the celebrity and public exposure he gained from being VP and his training as a journalist and utilize the same tactics the oil industry fat cats. Give the guy credit, he won a nobel prize, an oscar, a pulitzer, plus he's worth several hundred million dollars --- and he's trying to save the world.

I sincerely hope you never go into any form of teaching where language usage details matter. Pull your head out your ass.

You had better inform Lord Alfred Tennyson, who made frequent use of the technique of verbing. And I had better not catch you telling anyone to "just google it", as Google is a proper noun, not an adjective. Nor should I catch you saying that you will "email" something to somebody. As we know, the proper phraseology is to send someone an email, "email" being a noun, and not a verb.

Or you can accept that the concept of verbing words predates you AND the stick you rode in on, and cease insulting people needlessly in a sputtering rage.